Two basic approaches to endoatmospheric non-nuclear destruction of an incoming missile or aircraft are 1) hit-to-kill by directly impacting the target with a large, heavy interceptor mass at high velocity, and 2) blast-fragmentation involving multiple impacts of small fragments at very high velocities and strike angles (from the interceptor's nose) resulting from the explosion of a high explosive warhead in the interceptor in the vicinity of the ballistic missile.
The hit-to-kill or kinetic energy technology approach is based on the fact that when one object strikes another object at high speeds, a tremendous amount of destructive energy is released. The impact of an interceptor missile with an incoming tactical ballistic missile, aircraft, or cruise missile, can result in the total disintegration of both vehicles. Such impact can literally vaporize even metals. In contrast, blast-fragmentation warheads may only redirect or break up the target vehicle. However, even with a large hit-to-kill interceptor, the effective impact window is relatively small.
Cordle et al, U.S. Pat. No. 3,498,224, discloses a fragmentation warhead comprising a solid high explosive charge surrounded by a series of five axially spaced steps, with each of four of the steps containing a different number of circumferential layers of steel cubes to yield a fragment beam pattern made up of fragments having varying velocities. As illustrated in FIG. 5 of Cordle et al, each of the deployment velocities is substantially greater than the missile velocity V.sub.M. The five steps could be considered to be five separate warheads joined in tandem, with each warhead section employing a different uniform charge-to-metal ratio. The fragmentation pattern presented to an area some uniform distance away (large in proportion to the size of the warhead) is said to be extremely dense and in a relatively narrow beam on the order of 10.degree. wide. The fragments are identified as 3/16 inch steel cubes, with the weight of each of the fragments being 13 grains.
Thomanek, U.S. Pat. No. 3,474,731, describes a fragmentation warhead for use against personnel in an armored target. The warhead has a fragmentation casing arranged to separate into a multiplicity of elements upon detonation of the high explosive charge. The elements, which can be embedded in a synthetic resin, can be spherical, disk-shaped, or irregularly shaped. The fragmentation casing can be configured to direct the fragmentation elements in a number of specific directions.
Kempton, U.S. Pat. No. 4,026,213, discloses an aimable warhead having a thin metal outer skin and a stronger inner metal casing. The high explosive is contained in the annular space between the two shells, and is in contact with a plurality of circumferentially spaced initiators. A selected initiator can be fired to rupture an arcuate section of the outer skin while not causing a detonation of the main charge, and then another initiator can be fired to detonate the main charge, thereby fragmenting the thicker inner casing and driving the fragments through the ruptured arcuate section.
Throner, Jr., U.S. Pat. No. 3,263,612, describes a fragmentation weapon wherein the fragments in a first group of fragments are large in size and the fragments in a second group of fragments are smaller in size. The fragments can be positioned about a charge of high explosive and initially bonded together by a matrix of plastic resin and then covered with a sheath formed from fiberglass impregnated with plastic resin. Each of the larger fragments can have a mass of about 140 grains while each of the smaller fragments can have a mass of about 30 grains. Although the shape of the fragments is stated to not be critical, cubes are preferred.
Raech, Jr. et al, U.S. Pat. No. 4,430,941, describes a projectile in which packs of flechettes are supported by a frangible matrix of small smooth glass microspheres bound together and to the flechettes by resin. The matrix prevents the flechettes from being damaged during acceleration of the projectile.
Bourlet, U.S. Pat. No. 4,303,015, describes a pre-fragmented explosive shell wherein a plurality of balls is housed in an annulus about a high explosive charge. The balls can have a tungsten or tungsten carbide core with a zirconium coating.
While the foregoing patents disclose warheads producing fragment patterns utilizing discrete small pre-formed fragments, none discloses the use of a "slow" or low explosive propellant to radially deploy a plurality of precisely shaped high mass objects at low velocities to provide a desired dispersed pattern of the objects, whereby the effective hit-to-kill window is enhanced.